The disclosed embodiments of the present invention relate to controlling impedance matching, and more particularly, to an apparatus and method for controlling impedance tuning by using a hybrid control algorithm.
Antennas can be used to transmit radio frequency (RF) signals over the air when wireless communication devices are operated in the transmit (TX) mode. However, an antenna used in a wireless communication device (e.g., a mobile phone) may lose efficiency due to certain factors. For example, the impedance mismatch between the antenna and the front-end module may result in antenna performance loss. For another example, the human body (e.g., head and hand) may affect the antenna impedance, thus also resulting in antenna performance loss. In reality, the environmental condition of the wireless communication devices may vary from time to time, which greatly affects the antenna performance. When the antenna performance is degraded in the TX mode, a power amplifier is required to output an RF signal with a larger TX power to compensate the antenna loss. As a result, the current consumption of the power amplifier is increased. When the wireless communication device is a portable device powered by a battery, the battery life is short, which results in a bad user experience of using the wireless communication device.
Some of the lost antenna performance may be recovered with antenna tuning. The wireless communication device can use dynamic impedance tuning techniques to improve the antenna performance. However, the proper control of the antenna tuning is essential for the improvement of the antenna performance. If an antenna tuner is not properly controlled, the antenna may fail to have the desired performance gain. Thus, there is a need for an antenna tuning control scheme capable of properly configuring the antenna tuner to maximize the delivered power to the antenna.